It sounded like a good opportunity for a 20-year-old British model. Come to Milan for a photo shoot.

It was set up by her UK modelling agency, supposedly for an ad campaign.

What happened next, though, is out of a horror film.

According to Italian investigators, when the woman – who has not been named to protect her privacy – arrived at a flat for the shoot, Lukasz Herba and another man injected her with Ketamine, an anaesthetic drug used to sedate horses. After she passed out, Herba and his accomplice stripped and photographed her. They then covered her head with a pillowcase, taped her mouth shut, stuffed her in a suitcase and drove her in a car boot to an isolated house about 190km outside Milan.

“Think what could would have happened if she suffered from asthma,” Italian prosecutor Paolo Storari said.

The victim was handcuffed to a chest of drawers and kept in a bedroom for six days, investigators say. The space was rented using false documents, according to Italian media reports.

While she was trapped, Herba took pictures of her – many while she was drugged – and posted them on a secret website on the dark web. On that page, he tried to auction her off at a starting price of US353,000 in bitcoin.

He also reached out to her modelling agency demanding US$300,000 to stop her from being sold at auction.

“Attacked, drugged, handcuffed and closed inside a suitcase, that’s how a 20-year-old English model was kidnapped on July 11 in Milan to be sold to the best offer on pornography sites,” on the internet, a police statement said.

The woman was released, reports say, only after her captives found out that she was a mother.

“You have a two-year-old child and our rules exclude mothers,” the kidnapper supposedly told her, according to a report in the Corriere della Sera newspaper.

But a police official, Lorenzo Bucossi, told reporters it was ­unclear why the woman was ­released or whether a ransom had been paid. After she was freed on July 17, the kidnappers are said to have threatened to kill her if she told anyone and made her sign a contract promising that she would pay US$50,000 in bitcoin before the end of the month

Herba accompanied her to the British consulate in Milan, according to the newspaper. He was arrested the next day by police who had been alerted by the model’s agent and were investigating the kidnapping. He reportedly has since confessed to the kidnapping for extortion.

“The psychological pressure on the girl has been extreme,” Serena Ferrari, a police officer in Milan, told The Telegraph.

“She was very afraid.”

Police say there may be other victims. After Herba’s capture, authorities searched his computer and phone.

They reportedly found a cache of photos of the woman, including some while she was living in London. Investigators also say they found evidence that Herba is a member of the “Black Death Group,” an organisation that traffics people illegally on the dark web, and had organised other auctions for kidnapped girls.

According to the BBC, it’s not clear whether the other women exist or were invented by him.

“Fantasist or not, what is clear is that he is a very dangerous man,” Milan deputy prosecutor Paolo Storari told a press conference.

Herba is a 30-year-old British resident who was born in Poland. He was arraigned in a Milan court on charges of kidnapping and illegally holding a person captive.